The process of fiting some statistical model to a particular set of data. Mostly done on a computer, and using varied numerical methods such as optimization or numerical integration, or simulation.

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12 views

Support of distribution (distribution fitting)

This might be a weird question. I want to know why Matlab still run to produce estimated parameter whenever I input data which doesn't belong to the support of the distribution? E.g. I want to ...
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32 views

Probability of a point fitting a line

I am trying to classify between two groups a set of points given two variables (size of the space = L and points of the space occupied = N). At the moment I have a sample size of 620 samples with ...
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5 views

Reasonableness of a “fit” with more free parameters than fit targets?

I have a (physics) model with 19 free parameters, but only 12 experimental values (= fit targets) that need to be reproduced by the model. This be more precise: 19 parameters are put into ...
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31 views

Best linear fit [duplicate]

Which one is the best fit according to these information? fit1 or fit2. I am NOT working with this in an academic context so explanations are not important to me.
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11 views

Explanatory power of variable

To clarify from the very beginning, I expect relations between my variables to be very non-linear, so usual correlation and PCA approach may not work here. Also, for simplicity all the variables are ...
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8 views

Best-fit plane for a set of points

I have a set of 3D points, ie: $P\{(x_1, y_1, z_1), ..., (x_N, y_N, z_N)\}$. Each point in the set is a stellar object, and the $(x,y,z)$ system is defined from their equatorial coordinates and ...
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44 views

Fit generalised extreme event distribution in MATLAB/R

I have a location-scale t-student distribution $X$ $$ f(x,\mu,\sigma,\nu) = \frac{1}{\sigma} \frac{\Gamma(\frac{\nu+1}{2})}{\sqrt{\pi\nu} \Gamma (\frac{\nu}{2})} \left( 1 + \frac{(x - ...
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32 views

Data Fitting using R Code

I'm trying to use a copula function but I do not have the equation for my data, I just have all my raw data. Since my data is not normal, I tried fitting it into a normal distribution using the ...
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11 views

interpretation of inconsistent CFA fit indices

I'm working on a CFA seeking to assess the factor structure of an "improved" version of a personality questionnaire in a new sample. N = 225. Fit indices for the hypothesized two-factor structure ...
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27 views

How to improve the model of a fit to a sinus modulated sinus

I am trying to determine the amplitude of a sinus modulated sinus as accurate as possible. My sampling frequency is sufficently high and I am currently using a LSQ fit. The entire model looks as ...
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1answer
27 views

Two models of different data (sub)sets significantly different?

I need to see if different fits of different data sets are significantly different, preferrably in R. I have sample series A, B and C. These are different in length and all contain variables n, m, o ...
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1answer
57 views

Forecasting and making sense of data

This might seem very elementary or even silly, but all comments are much appreciated. As science major I do not have deep technical knowledge in statistics, so any guidance is much appreciated. Say ...
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1answer
40 views

R: How to estimate the parameters of a Gamma distribution, knowing the empirical cumulative distribution

I have been given an empirical cumulative distribution, and I need to fit a Gamma distribution to it using R. By trial-and-error (and using Excel's Solver), I know that's possible, but I need to ...
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1answer
22 views

Fit distribution to grouped data with unequal intervals

From a social network survey (name generator and name interpretor) I have data about frequencies of interaction ("How often are you in contact with person X?") on a scale I would interpret as interval ...
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1answer
36 views

Rule of thumb for choosing best fit indeces in cfa

I read this intetesting page about fit indices in SEM. There are lot. It seems that the RMSEA is one you should always report, but how to choose the other ones? Is there some kind of rule of thumb? ...
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1answer
42 views

Right skewed asymmetric Gaussian-like distribution

I am trying to find a possible candidate as a fitting function for a distribution that looks like the following I know that this isn't a straightforward question, but I would like a simple function ...
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0answers
12 views

Choosing correct (or at least precise) order of Fourier series

I'm currently trying to learn to analyse periods of certain variable stars using their magnitudes. I stumbled upon a tool that analyse and calculate the periods using the data set supplied but there's ...
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0answers
48 views

Mixture of beta distrubutions

I have data; one column and 310 rows. When I plot the histogram, it has two peaks; see the figure. I would like to find appropriate distribution that fits the data. I tried to mixtools in R, but it ...
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0answers
9 views

Basis for fitting a complete monotone

I have set of measured data: x=[x1,x2,....,xn] y=[y1,y2,....,yn] It is a multi component data. However I need to fit for only one component which is known to ...
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1answer
67 views

How to measure the goodness-of-fit of a nonlinear model?

Well… I did search for a while before asking and noticed perhaps my question itself has something basically wrong after reading this and this but still not sure so decided to cry out loud :). As ...
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2answers
321 views

Regression: Scatterplot with low R squared and high p-values

Based on three datasets, I have produced the scatterplot below in Python: I am trying to fit a line on each dataset, but when I check the metrics this is what I get: Set 1 (red): R squared=0.002, ...
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0answers
39 views

Finding a “skew normal distribution” for given data

I am given a set of $n$ pairs $(x_i, y_i)$, where the $x$-coordinates can be interpreted as the measured values of a random variable $X$ and the $y$-coordinates can be interpreted as some "scaled" ...
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9 views

Linear regression with different samples of data: addressing compatibility and parameter estimation

I have two samples of data (call 'em black and red), spread like in figure. I ran a linear regression over both samples. I understand that they cannot come from the same joint pdf f(x,y), and that a ...
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29 views

Compute the coefficients of a generalized linear model

I am using the R stats package to fit a generalized linear model by means of the function glm. But what I really need is only to ...
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0answers
10 views

Using a model with domain/image constraints [duplicate]

I would like to fit a model and the smallest predicted value must be zero. This is what I have done: ...
2
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1answer
28 views

Fitting data while accounting for error in data

I have data that has error. The error bars in the data represent one standard deviation. I would like to fit a line to these data, while accounting for the fact that the data could vary between my ...
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1answer
50 views

How can I calculate confidence intervals of a probability obtained by my logistic regression model?

I have fit my own logistic model and I am using it to calculate the probabilities of different outcomes. I would like to know how I can obtain the confidence intervals of these probabilities. I am ...
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1answer
26 views

Determining which of my two fit functions is better (python)

I am working on a python project right now, and it entails me fitting Gaussian curves with either a one component fit or a two component fit. Sometimes, the data just doesn't have two components in ...
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14 views

Fitting test data to ground truth data

I have 2 sets of 3D imaging data from the same sample of biological tissue. Set A was gathered using an established method, and set B was gathered using a new, unvalidated method. My goal is to locate ...
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39 views

Social Science: Data Fitting and Prediction in Regression Analysis

Statistical methods are also used in the social science and in my major, Political Science, researchers often use regression and related techniques. They run regressions for the collected data and ...
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1answer
101 views

What do I fit to a heavily positively skewed histogram?

I have a data which has heavily positively skewed variables. My manager has told me to fit it some distributions (univariate). The problem is that for most of the data the mean is far closer to the ...
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2answers
43 views

Can I fit logistic regression over a dataset with only categorical data?

I have a dataset which contains only categorical data i.e.A,B,C,D (like factors) for each predictor. There are 10 predictors and the dependent variable is binary, ...
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22 views

Fit oscillating data and predicting values

I have an oscillating variable which I'd like to fit. ...
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0answers
16 views

Are there any model fitting procedures that can be updated with new data? [duplicate]

Not sure if this is the right place for this question but I was wondering whether there are any model fitting procedures (any at all!) that can 'update' when a new data point is obtained? The reason ...
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1answer
50 views

Fitting a linear relationship, not a standard linear regression model (in Python)

I want to learn about the relationship between 3 categorical variables (a, b, c). I have pairs of such triples that appear together. Ie.: $$ ((a_1, b_5, c_3), (a_3, b_5, c_7)) $$$$ ((a_2, ...
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117 views

Fitting data to multimodal distributions with scipy, matplotlib

I have a dataset that I would like to fit to a known probability distribution. The intention is to use the fitted PDF in a data generator - such that I can sample data from the known (fitted) PDF. ...
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1answer
55 views

Calculating $R^2$ for exponential regression in R

I am fitting a simple regression model on my data and I am using nls() the only problem is it does not provide the coefficient of determination $R^2$ and adjusted ...
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0answers
8 views

How to have an edge with a date attribute?

I have a question about fitting power-law distribution. I am working on a large graph and I have computed the distribution of vertex degrees. The Kolmogorov-Smirnov test rejects the fitting to a ...
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1answer
40 views

How to choose what copula to use for a certain application?

I'm using the copula package in R for modelling dependece using copulas. 1)What is the suggested course of action for choosing a copula model? 2)Should I use the function ...
2
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1answer
103 views

What's the difference between averaging data then fitting and fitting the data then averaging

I wanted to know what the difference is, if any, between fitting a line to multiple separate "experiments" then averaging the fits, or averaging the data from the separate experiments then fitting the ...
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1answer
30 views

Automatically find the best growth (linear, quadratic, exponential, etc.) to fit the points [duplicate]

Suppose there is a set of points $[(x_1, y_1),(x_2, y_2), ..., (x_n, y_n)]$. I want to figure out whether $y$ will grow with $x$. If yes, I want to automatically find the best growth (linear growth, ...
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1answer
33 views

Fitting of distributions [closed]

I have a dataset containing 50 datapoints to which I need to fit some non-standard continuous distributions (the functional form is known) using maximum likelihood estimation. I presume there are ...
2
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0answers
31 views

An alternative to a regular poisson distribution for count data.

I'm trying to find out what distribution my empirical count data fits. Scores can run from 0-8 and I have ~360 observations. I've been using the fitdistrplus ...
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0answers
23 views

Why fitting does not find the true best point

I fitting an expression of the form: $s(t)=\frac{1}{1+\exp[a+\sum_k b_k x_k(t)]}$ Where $a$ and $b_k$ are fitting parameters and $x_k(t)$ an input time series. I have $k=1,...,N$ different types of ...
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73 views

Interpreting steep histogram, fitting distribution

I'm trying to fit the distribution to the data. I started with histogram. Note that y axis is in logarithmic scale since the histogram is very steep. How should proceed to find actual ...
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0answers
11 views

Fitting data with interdependence

I have an issue, of which I'm not sure how can be solved. I'm trying to do so with Mathematica (and their stack exchange recommended I try here), but other solutions are also possible of course. ...
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0answers
12 views

Comparison between coefficients of 2 polynomial fits

I have a cancer data according to men and women. I fit cancer incidence polynomially to men and women separately based on year. And I get 2nd order year coefficients for men as -3.04e-4 and -6.10e-4 ...
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1answer
127 views

Fit truncated Poisson distribution in R

I am trying to fit a Poisson distribution with zero-truncated, imperfectly observed data. I have a set of samples for which I can observe 1 counts and >1 counts, although I don't know what the >1 ...
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33 views

are there anomalies? and if so, can I quantify them?

Given a data set, I want to divide it in two different sets if I see that part of the data misbehaves. For example, in the figure you can clearly see that something is happening before the vertical ...
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1answer
206 views

How to fit a function to a CDF in R?

I've been given a dataframe that contains data for a CDF. The column X contains the 250 $X$ values, and the column P contains ...